Patogenesis of tinnitus in patients with post-COVID syndrome - preliminary report

Introduction: Similarly to hearing loss and dizziness, tinnitus is a frequently reported complication of COVID-19 and remains the subject of numerous scientific reports. However, the exact impact of SARS-CoV-2 on the pathophysiology of tinnitus observed in post-COVID syndrome remains unclear. One suspected cause behind the development of vestibulocochlear symptoms is the inflammation of neural tissue triggered by SARS-CoV-2 infection. Aim: The aim of this study was to analyze the results of Brainstem Auditory Evoked Potentials (BAEP) in the context of tinnitus development among patients diagnosed with post-COVID syndrome. Material and methods: This retrospective study involved the analysis of BAEP test results of patients admitted to the Audiology Clinic of the Military Institute of Medicine at the National Research Institute and diagnosed with the post-COVID syndrome. The study compared the average latency values of waves I, II, III, IV, V, and intervals I-III, III-V, I-V. The statistical analysis of the obtained data was performed. Results: Out of 18 patients (9female, 9 male) with an average ageof 54.22 years (+/- 9.65) diagnosed with post-COVID syndrome, tinnitus was identified in 5 individuals (27.78%). A statistically significant increase in wave V latency (5.98 vs. 5.63 [ms]; p < 0.05) and interval III-V (1.99 vs. 1.71 [ms]; p<0.05) was observed between the groups of patients with and without tinnitus,respectively.This observation was notdocumented in the control group comprising27 patients who were diagnosed before the outbreak ofthe COVID-19 pandemic. Discussion: Study results analyzing BAEP changes in patients with post-COVID syndrome in the context of tinnitus are insufficient in current literature. The only available report linking post-COVID syndrome with sensorineural hearing loss demonstrated a statistically significant increase in latency values of waves III, V, and an increase in intervals I-III, III-V. Conclusions: Tinnitus in patients suffering from post-COVID syndrome may be related to prolonged conduction of nerve impulses within the brainstem auditory pathway. Detailed pathophysiology of these changes requires further research.